Liver Transplants, Nitrous Oxide and Pig Cells

If you think you might have a liver transplant in your future, there are a few pieces of good news this week.

At Ohio State University, researchers announced they are developing technology for keeping liver cells alive and functioning normally inside bio-artificial liver-assist devices.

These allow people suffering from acute liver failure to survive while their own liver cells regenerate, or they receive a liver transplant. The person’s blood or plasma circulates through the device. Inside, living cells, typically pig or human liver cells, do normal liver functions.

For those liver cells to keep working, they need oxygen. Andre Palmer, an associate professor of chemical and biomolecular engineering at Ohio State, and his team are developing innovative ways to chemically modify and package hemoglobin — the blood molecule in red blood cells that transports oxygen — to deliver oxygen to liver cells in just the right way.

His solution has been to create different kinds of hemoglobin. One he seals inside microscopic polymer capsules; oxygen bound to the hemoglobin diffuses through the polymer over time to reach liver cells. Another is a type of hemoglobin-based oxygen carrier, which consists of long chains of hemoglobin molecules wound into balls that can then transport oxygen to liver cells.

Inhaled Nitrous Oxide

Another study, researchers at the University of Washington, and the University of Alabama suggests one complications of liver transplantation can be treated just by having patients getting transplants inhale nitric oxide (NO) during the operation.

“Inhalation of NO decreased the length of time the patients had to stay in hospital and increased the rate at which the function of the transplanted liver was restored, leading the authors to suggest that inhalation of NO is a valuable preemptive approach to enhancing liver function after transplantation.”

Ischemia/reperfusion injury is one of the main causes of liver dysfunction and failure after transplantation, and is linked with decreased nitrous oxide production in the liver. The study was published in the Journal of Clinical Investigation.

Age No Barrier

Another study, published in the August issue of the journal Archives of Surgery, reveals that age on its own does not raise the risk of death of liver transplant patients age 70 or older, and also should not be a restriction on liver transplantation for elderly patients.

Researchers at University of California, Los Angeles, David Geffen School of Medicine analyzed medical records of 62 patients age 70 and older, and 864 patients ages 50 to 59. 31 of the 62 patients in the study aged 70 and older, and 345 of the 864 younger patients died during the study period.

After one year, 73.3 percent of older patients and 79.4 percent of younger patients were alive. 10 years following surgery, 45.2 percent of younger patients and 39.7 percent of older patients were still alive.

According to the study, this means there is “no statistically significant difference in survival in the first 10 years after transplantation” between the two patient groups. Of 26 variables analyzed, four were found to be predictive of liver transplant patient death. These were a preoperative hospitalization; a prolonged period of cold storage between liver removal and transplanting; cirrhosis caused by hepatitis C and alcohol; and an increasing model for end-stage liver disease (MELD) score, a standard measure for disease severity.

“In conclusion, biological and physiological variables may play a more important role than advanced age in predicting poor survival after liver transplantation,” the team wrote. “Measures of physiological age and risk of complications should be used in the evaluation process of elderly transplant candidates. Age by itself should not be used to limit liver transplantation.”